Method and apparatus for the generation of refrigerating energy

ABSTRACT

The present invention relates to a method of and an apparatus for the generation of refrigerating energy. There are arranged two columns provided with adsorbent products; an adsorbed gas is sucked into a first column and delivered into a second column and vice versa, and a closed circulation of helium is created in said columns in counterflow with the adsorption-desorption gas and to the exterior in contact with conducting means.

United States Patent Inventor Emile Carbonell Grenoble, France Appl. No. 15,433

Filed Mar. 2, 1970 Patented Jan. 11, 1972 Assignee L'Air Liquide, Societe Anonyme Pour IEtude et lExploitation des Procedes Georges Claude Paris, France Priority Mar. 14, 1969 France 6907355 METHOD AND APPARATUS FOR THE GENERATION OF REFRIGERATING ENERGY [50] Field of Search 62/48, 79, 113, 1 14, 467, 514, 86, 401

[56] References Cited UNITED STATES PATENTS 3,397,549 8/1968 Daunt 62/467 X Primary ExaminerWilliam F. ODea Assistant Examiner-P. D. Ferguson Anarney- Young and Thompson ABSTRACT: The present invention relates to a method ofand an apparatus for the generation of refrigerating energy. There are arranged two columns provided with adsorbent products; an adsorbed gas is sucked into a first column and delivered into a second column and vice versa, and a closed circulation 10 Claims 4Drawin Fi s.

g g of helium is created in said columns in counterflow with the US. Cl 62/79, adsorption-desorption gas and t0 the exterior in contact With 2/ 2/ 2/467 conducting means. Int. Cl F25b 9/00 26 2s Y-7 7/ 20 81 1k,- 17' 27 a a 27 1s 15 13h I 13b 1. 1.

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PATENTED JAIN 1 I972 SHEET 3 0F 3 must 514/1 6 Cam 5M5 METHOD AND APPARATUS FOR THE GENERATION F REFRIGERATING ENERGY The present invention relates to a method of and apparatus for the regeneration of refrigerating energy at very low temperature, utilizing refrigerating emission during the desorption of a gas.

A method has already been proposed for recovering the refrigerating emission during desorption of a gas, having available a hot source at a temperature of the order of K., and causing a mass of adsorbent products to absorb and desorb successively, the said mass being successively brought during the course of these operations from the hot temperature to a colder temperature. While this method of operation enables very low temperatures to be reached, it has not however a very satisfactory power efficiency.

The present invention relates to a method of generation of refrigerating energy at very low temperature which has a considerably improved power efficiency and which enables temperatures to be obtained still lower than those which were possible in known methods, based on the same principle.

The method according to the invention is especially characterized in that there are arranged at least two columns of thermally insulated chambers provided with adsorbent products, the said adsorbent products being associated with heat-conduction means in the transverse direction of the said columns; in that the adsorbed gas is sucked into a hot extremity of a first column, and is delivered into a corresponding extremity of at least one second column; then in that the suction and delivery circuits are reversed in a cyclic manner; in that the heat emission appearing in a zone adjacent to a section-delivery orifice associated with the column in course of adsorption, is evacuated towards the exterior; and in that there is created a closed gas circulation at a very low liquefaction temperature partly longitudinally in the interior of the said columns and in good thermal contact with the said heat-conduction means, partly to the exterior of the said columns while coming into contact with a member forming a cold source, the said closed circulation being effected in the said columns in counterflow with the adsorption-desorption gas.

As will be explained later, this arrangement makes it possible to carry out the operations of adsorption and desorption of adsorbent products which are maintained at a substantially constant temperature ranging between the hot temperature and the cold temperature.

According to the invention, helium is employed as the gas for the said closed circulation.

The invention has also for its object a refrigeration generator characterized in that it comprises at least two columns equipped with adsorption means on supports having essentially radial heat conductivity, and closed circulation means for a gas in heat transfer with exchangers arranged longitudinally in each column in contact with the said supports, means for transferring the adsorption-desorption gas from one column to another column, and means for putting the gas into circulation in a closed circuit, and in a cyclic manner, always in counterflow to the circulation of the adsorption-desorption gas in the said columns, together with means for evacuating heat towards the exterior in the zone in which the suctiondelivery of the gas is effected.

The characteristic features and advantages of the invention will be further brought out in the description which follows below by way of example, reference being made to the accompanying drawings, in which:

FIG. I is a diagrammatic view of an adsorption-desorption refrigeration generator according to the invention;

FIG. 2 is a partial diagrammatic view of an alternative form of construction;

FIG. 3 is a diagrammatic view of a second alternative form of construction;

FIG. 4 is a view in partial cross section and to a larger scale of a detail of an adsorption column.

Referring now to FIG. 1, a refrigeration generator comprises two columns 1 and 2, each consisting of two chambers 3 and 4, 3 and 4, thermally insulated, the chambers 3 and 4 on the one hand and 3' and 4' on the other being connected to each other by a conduit 5, 5' and by a conduit 6, 6 to a coil 7, 7 respectively of a first exchanger 8, 8' and then to coils 9, 9 of a common exchanger 10, and from thence to two valves II, 12 on the one hand and two valves 11', 12 on the other, the valves 11 and 12 being connected to the high-pressure outlet of a compressor 13 of the refrigeration type, using water for example, while the valves 11' and 12 are connected to the low-pressure admission of this compressor 13. Thus, by opening the valves 11 and 11, while the valves l2, 12' are closed, a gaseous fluid can be sucked out of the chambers 3' and 4' and delivered in the direction of the arrow f toward the chambers 3 and 4, while the reverse operation takes place when the valves 12, 12 are opened and the valves 11, II are closed.

In each of the chambers 3, 3', 4, 4' are placed stacks of adsorbent products, rigidly fixed to supporting means forming heat conductors, the whole being arranged, at least in the chambers 3 and 3', in such manner that the heat conduction takes place in the radial direction of the column, while interruptions in heat conduction are ensured in the longitudinal direction.

For the construction of the stacks of these adsorbent products, conductive winding of tape in the form of pancakes are advantageously employed, and on these conductive pancakes are encrusted grains of adsorbent product. Conductive tapes of this kind with an encrusted layer of adsorbent product, having the form of pancakes, are described in the U.S. Pat. application Ser. No. 837,5 l 7 ofJune 30, 1969 in the name of the present applicants for Gas-adsorbing element and its method of manufactures.

As will be more clearly seen from FIG. 4, in the chamber 3 (3') there is arranged a stack, of pancakes for example, 13a, 13b, 13g, l3'a, 13b 13'g respectively with the interposition between each winding l3a-I3b or 13b-l3c, etc., of heat insulation means which are however permeable to the gas, for example, perforated insulating spacers 40, as shown in FIG. 4. In the chamber 4 (4), it will be sufficient to arrange one or more pancakes of adsorbent product 13):, l3h, without taking any steps to ensure heat insulation in the longitudinal sense.

In the chambers 4 and 4 is arranged a first nest of tubes l5, l5 supplied from a tank 16 of cryogenic liquid, for example, liquid nitrogen and adapted to vaporize this cryogenic liquid, the vapors of which flow through a pipe l7, 17', a coil 18, 18 of the exchanger 10 and a valve l9, l9. Changeover switching means (not shown) successively ensure the opening of the valve 19 and the closure of the valve 19', when the adsorptiondesorption gas is delivered into the column I, and the closure of the valve 19 and the opening of the valve 19, when this gas is delivered into the column 2. This tank 16 is in turn in communication with an escape conduit 20 to the open air through a coil 21 of the exchanger 10.

A closed circuit for a gaseous cryogenic fluid with a very low vaporization point, for example helium, is established from one or the other of the circulators 24, 25 immersed in the bath of liquid nitrogen in the tank 16, through a coil 26, 26' of the exchanger 8, 8' respectively, a coil 27, 27 in the isothermal chamber 4, 4 respectively, and a coil 28, 28 in the chambers 3, 3' respectively, with an external connecting tube 29 between the two columns 1 and 2, cooperating with a member 30 constituting the cold source.

The operation of the device is as follows:

The apparatus operates like a rocking device from the point of view of the phenomena of adsorption and desorption. Thus, during one phase, the fluid of adsorbed and desorbed gas, which is a mixture of helium and hydrogen for example, is propelled by the compressor 13 in the direction of the arrow f, that is to say the gases passing through the stacks of adsorbent l3'a, I3'b l3'h of the chambers 3' and 4 desorb under depression, while the stacks 13a, 13b. 13!: of the chambers 3 and 4 under pressure adsorb the gas which has just been desorbed after recompression. During the course of this phase, the circulator 24 is in motion and the circulator 25 is stopped, so that the gaseous helium circulates in the direction V, namely in counterflow to the current of adsorbed and desorbed gas in the columns 1 and 2.

In the following phase, the compressor 13 sucks in the gas which is desorbed from the stacks of adsorbent 13a, ll3b 13h of the chambers 3 and 4 and delivers it into the stacks of adsorbent l3'a l3h of the chambers 3 and 4' in which the gas is adsorbed.

During this phase, the circulator 24 is stopped and the circulator 25 is started up, so that the gaseous helium circulates in the direction V, that is to say always in counterflow to the gaseous movement of adsorption-desorption.

During the course of all the phases, the valves l9 and 19 are successively opened so that the heat evolved during the adsorption phases is evacuated by vaporization of the liquid nitrogen. There is of course no circulation of liquid nitrogen in the circuit (15') associated with the column 1 (2) during the course of desorption. All the operations of adsorption and desorption are thus effected in the chambers 4, 4' at constant temperature (warm temperature).

On the contrary, it is found that the other extremity of the columns 1 and 2 is at cold temperature, with a uniform temperature gradient between the two extremities of each column I and 2, and that there is developed, at the level of the member 30, a certain refrigerating power available at a very low temperature.

The phenomenon can be explained in the following manner:

In the phase at which the stacks of adsorbent product 13'a, 13'b ll3'h desorb a gas, there is produced a refrigerating emission due to the phenomenon of desorption, whereas when simultaneously this gas is adsorbed into the stacks of adsorbent product 13a, 13b 13h, there is produced a calorific emission.

The result is that the cooling produced by the desorption of the gases in the adsorbent stacks l3'a, 13'!) 13h is evacuated on the one hand by the gaseous transfer flow circulating in the coils 27 and 28, and on the other hand by the gas flow of adsorption-desorption passing out of the columns 3 and 4 by the conduit 6. This latter emission by the conduit 6 is transferred from the coil 7 to the coil 26 in the transfer fluid (exchanger 8), so that the cold produced during the desorption phase is wholly transferred (except for the degree of irreversibility of operation of the exchangers) to the transfer fluid circulating in the coils 27, 28.

This transfer fluid gives up a part of this cold to the cold source 30, the other part of this cold being employed to evacuate the emission of heat which takes place in the adsorbent stacks 13a 13g, while that which occurs in the stack 13!: is evacuated by the vaporization coil 15 of liquid nitrogen, solely in service in the column in course of adsorption. During the course of the following phase, the functions are reversed, with a change in the direction of circulation of the flow of transfer fluid (circulator 24 stopped, circulator 25 in operation) and the opening of the valve 19', while the valve 19 is closed.

It will be noted that the enthalpy available at. the source is equal to the difference in enthalpy between the low-pressure gas flowing towards the suction of the compressor 13 at the warm end of the exchanger 8', and the enthalpy of the highpressure gas, calculated in the following manner:

Enthalpy of the high-pressure gas between the chambers 4 and 3, to which is added the enthalpy of the high-pressure gas in the adsorbed form in the chamber 4.

In the present case in which the warm source is liquid nitrogen at 77 K. for example, the gaseous mixture treated by the compressor may comprise helium and hydrogen and/or neon, in proportion such that a high thermal effect is obtained during the adsorption and the desorption in the zone of temperature in the vicinity of 77 l(., in the chambers 4 and 4.

The hydrogen will be essentially adsorbed in the chamber 4 or 4, the remainder being adsorbed in the warm zone or the regenerators 3 or 3'. The helium will be essentially adsorbed in the cold zones of the regeneration chambers 3 or 3'.

The temperatures which can be reached at the source 30 are a function of the laws of adsorption and desorption in the regenerators 3 and 3', and also of the degree of irreversibility of the device in respect of heat exchanges. The method employed makes it possible to obtain temperatures as low as 20 K. or even 6 to 10 I(., by utilizing adsorbent cycled between a high pressure equal to or higher than 10 bars and a low pressure less than I bar, but as close as possible to this value.

According to an alternative form of construction (FIG. 2), even lower temperatures may be obtained by putting the bot toms of the columns 3 and 3 into communication, as indicated by the capillary 32, extending in contact with the source 30 and connected by the tubes 33 and 34 to the columns 3 and 3. This ensures an isoenthalpic expansion between the high-pressure and low-pressure columns 3 and 3'.

FIG. 3 shows a simplified construction of a refrigerating generator according to the invention, in which the main elements, which are identical with those described with reference to FIG. 1, have been given the same reference numbers. In this case however, the means for maintaining a warm temperature above the ambient temperature by means of liquid nitrogen have been dispensed with. On the contrary, the coils l5 and 15' are supplied by a single flow which is alternately distributed into one or the other of the coils l5 and 15' by a circulator 35, 36 respectively.

The applications of the method are as follows:

Refrigeration of electronic devices, detectors, superconductivity coils;

Refrigeration of electrotechnical devices operating at cold temperatures.

What I claim is:

l. A method of generation of refrigerating energy available at a very cold temperature, utilizing the refrigerating emission produced by the desorption of a gas in at least two columns of thermally insulated chambers provided with adsorbent products, the said adsorbent products being associated with thermally conductive means acting only in the transverse direction of said columns, and with heat-insulating gas-permeable means extending transversely at different levels in said columns, comprising sucking adsorbed gas into a warm extremity of a first column and delivering it into a corresponding extremity of at least one second column; reversing the suction and delivery circuits in a cyclic manner; evacuating towards the exterior the heat emission appearing in a zone adjacent to a suction delivery orifice associated with the column in course of adsorption; creating a closed circulation of gas at very low liquefaction temperature partly longitudinally in the interior of the said columns and in good thermal contact with the said thermally conductive means, partly to the exterior of the said columns while coming into contact with a member forming a cold source, the said closed circulation being effected in the said columns in counterflow with the adsorption-desorption gas.

2. A method of generation of refrigerating energy according to claim I, wherein helium is employed as the gas for the said closed circulation.

3. A refrigerating generator comprising at least two columns equipped with adsorption means on supports, said supports having essentially radial heat conductivity and further including heat-insulating gas permeable means extending transversely between said supports at different levels in said columns, and closed circulation means for a thermal transfer gas in heat transfer with heat exchangers arranged longitudinally in each column in contact with the said supports, means for transferring an adsorption-desorption gas from a suction-delivery extremity of one column to a suction-delivery extremity of another column and vice versa, and means for putting the thermal-transfer gas into circulation in a cyclic manner, always in counterflow to the circulation of the adsorptiondesorption gas in the said columns, and means for evacuating heat towards the exterior at the level of the suction-delivery extremities of the adsorption-desorption gas.

4. A refrigerating generator according to claim 3, wherein the heat-evacuation means are constituted by means for circulating a cooling liquid.

5. A refrigerating generator according to claim 3, comprising supports having essentially radial heat conductivity made of metal strips on which are fixed by incrustation said adsorbent products, and heat-insulating spacers separating said supports.

6. A refrigerating generator according to claim 4, wherein each column comprises two chambers communicating with each other, of which one, which is the chamber for introduction of the adsorption-desorption gases, is associated with a means for circulating a cooling liquid at constant temperature.

7. A refrigerating generator according to claim 3, wherein the means for closed circulation of the thermal transfer gas comprise, an exchanger in thermal cooperation with a part of the means for transferring the adsorption-desorption gas.

8. A refrigerating generator according to claim 3, wherein a the heat evacuation means comprise a heat exchanger in ther- 

1. A method of generation of refrigerating energy available at a very cold temperature, utilizing the refrigerating emission produced by the desorption of a gas in at least two columns of thermally insulated chambers provided with adsorbent products, the said adsorbent products being associated with thermally conductive means acting only in the transverse direction of said columns, and with heat-insulating gas-permeable means extending transversely at different levels in said columns, comprising sucking adsorbed gas into a warm extremity of a first column and delivering it into a corresponding extremity of at least one second column; reversing the suction and delivery circuits in a cyclic manner; evacuating towards the exterior the heat emission appearing in a zone adjacent to a suction delivery orifice associated with the column in course of adsorption; creating a closed circulation of gas at very low liquefaction temperature partly longitudinally in the interior of the said columns and in good thermal contact with the said thermally conductive means, partly to the exterior of the said columns while coming into contact with a member forming a cold source, the said closed circulation being effected in the said columns in counterflow with the adsorption-desorption gas.
 2. A method of generation of refrigerating energy according to claim 1, wherein helium is employed as the gas for the said closed circulation.
 3. A refrigerating generator comprising at least two columns equipped with adsorption means on supports, said supports having essentially radial heat conductivity and further including heat-insulating gas permeable means extending transversely between said supports at different levels in said columns, and closed circulation means for a thermal transfer gas in heat transfer with heat exchangers arranged longitudinally in each column in contact with the said supports, means for transferring an adsorption-desorption gas from a suction-delivery extremity of one column to a suction-delivery extremity of another column and vice versa, and means for putting the thermal-transfer gas into circulation in a cyclic manner, always in counterflow to the circulation of the adsorption-desorption gas in the said columns, and means for evacuating heat towards the exterior at the level of the suction-delivery extremities of the adsorption-desorption gas.
 4. A refrigerating generator according to claim 3, wherein the heat-evacuation means are constituted by means for circulating a cooling liquid.
 5. A refrigerating generator according to claim 3, comprising supports having essentially radial heat conductivity made of metal strips on which are fixed by incrustation said adsorbent products, and heat-insulating spacers separating said supports.
 6. A refrigerating generator according to claim 4, wherein each column comprises two chambers communicating with each other, of which one, which is the chamber for introduction of the adsorption-desorption gases, is associated with a means for circulating a cooling liquid at constant temperature.
 7. A refrigerating generator according to claim 3, wherein the means for closed circulation of the thermal transfer gas comprise, an exchanger in thermal cooperation with a part of the means for transferring the adsorption-desorption gas.
 8. A refrigerating generator according to claim 3, wherein the heat evacuation means comprise a heat exchanger in thermal cooperation with a part of the means for transferring the adsorption-desorption gas.
 9. A refrigerating generator according to claim 3, comprising cyclic changeover means synchronized with the direction of circulation of the adsorption-desorption gas and of the thermal-transfer gas.
 10. A refrigerating generator according to claim 9, further comprising means for intermittently putting into operation means for evacuation of heat towards the exterior in synchronism with the said cyclic changeover means, said means ensuring the operation of the heat evacuation means on the single column in course of adsorption. 